Method of constructing a nuclear reactor having reactor core and control elements supported by reactor vessel head

ABSTRACT

A nuclear reactor is designed to couple the load path of control elements with the reactor core, thus reducing opportunity for differential movement between the control elements and the reactor core. A core barrel can be fabricated in a manufacturing facility to include the reactor core, control element supports, and control element drive system. The core barrel can be mounted to a reactor vessel head. Movement, such as through seismic forces, transmits an equal direction and magnitude to the control elements and the reactor core, thus inhibiting the opportunity for differential movement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.17/164,820, filed Feb. 1, 2021, which claims the benefit of U.S.Provisional Patent Application No. 63/066,785, filed Aug. 17, 2020, bothentitled “CARTRIDGE CORE BARREL FOR NUCLEAR REACTOR,” the contents ofeach are incorporated herein by reference in their entirety.

BACKGROUND

Most nuclear reactors have a core within which fuel elements and controlelements are supported in different interrelated arrangements to supporta critical reactivity to control the output of the reactor. Coolant istypically forced through passages between fuel elements and controlelements to transfer heat generated by fissioning fuel elements to aheat exchanger to be used for useful purposes.

In some cases, molten metal is used as the coolant, which in some cases,is sodium. In some nuclear reactors, such as in a pool type reactor inwhich the core is submerged in a pool of coolant held within a reactorvessel, the core is often supported by the reactor vessel while thecontrol elements are often supported from a deck of the vessel head thatencloses the top of the reactor vessel.

This control element support arrangement is often preferable from asafety standpoint. For example, if the control element supportstructures were to fail, the control elements would fall into thereactor vessel and reduce reactivity within the core. Typically, theweight of the core is supported by the reactor vessel, as is thein-vessel handling system for the fuel elements and reactivity elementsalong with the fuel elements and reactivity elements.

In addition to the weight of the core, the vessel also supports theweight of the coolant contained therein. The vessel must therefore berobust in order to support the applied loads not only in staticconditions, but must also be able to support the loads during seismicevents, which can apply dramatically greater loads than in a staticcondition.

Moreover, any relative motion between the reactor core and the controlelements can impact the reactivity within the core, and thus, reactorsare designed to minimize relative motion between the core and controlelements. If a reactor vessel is supported from the side or its bottomand the coolant inventory is brought into motion, such as by a seismicevent, the flexibility of the reactor vessel can allow the reactor coreto move relative to the control elements suspended from the vessel head,thus causing swings in a reactivity coefficient (Keff) in both positiveand negative reactivity directions.

SUMMARY

According to some embodiments, a reactor layout is described in whichthe reactor vessel hangs from the reactor head; however, the weight ofthe core may not be supported by the reactor head, but rather, can betransmitted directly to supporting structures located outside thereactor vessel and supported by the earth. In some examples, the reactorcore is supported by a cartridge that is suspended from the reactorvessel head, thus coupling the load path of both the reactor core andthe control elements to a common support structure, which reduces thepotential of relative movement between the reactor core and the controlelements.

According to some embodiments, a nuclear reactor core support systemincludes a support cylinder, the support cylinder having an upperportion and a lower portion; and a mount at the upper portion, the mountconfigured to engage with a reactor vessel head and support the weightof the support cylinder from the reactor vessel head wherein the supportcylinder hangs from the reactor vessel head.

In some cases, a reactor core is within the support cylinder. Thesupport cylinder and the reactor core may be preassembled and shipped toa reactor installation site.

In some instances, a fuel element handling system is positioned withinthe support cylinder. Further, a control element support system may bewithin the support cylinder.

In some embodiments, the support cylinder and a control element drivesystem share a common load path. In other words, the weight of thesupport cylinder and the control element drive system is supported bythe same structure.

For example, the support cylinder and the control element drive systemmay both be suspended from a portion of the reactor vessel head.

In some cases, support for a reactor core located within the supportcylinder does not transmit a load to the reactor vessel. For example,the reactor core may be located within the support cylinder and theweight of the reactor core may be supported by the reactor vessel head.

According to some embodiments, a method for constructing a nuclearreactor includes the steps of fabricating, in a manufacturing facility,a reactor vessel; fabricating, in the manufacturing facility, acartridge core barrel; fabricating, in the manufacturing facility, areactor core; fabricating, in the manufacturing facility, a controlelement drive system; assembling, in the manufacturing facility, thecontrol element drive system and the reactor core within the cartridgecore barrel to create a core module; and shipping the core module to aconstruction site.

The method may further include shipping the reactor vessel to theconstruction site. In some cases, the method may include installing thereactor vessel in a reactor building. The method may further include thestep of placing the reactor module inside the reactor vessel.

The method of constructing a nuclear reactor may include, in some cases,coupling the reactor core module to a first portion of a reactor vesselhead. In some cases, the method includes coupling the control elementdrive system to the first portion of the reactor vessel head.

According to some embodiments, a below core support structure for anuclear reactor core includes a conical support portion; a cylindricalsupport portion coupled to the conical support portion by a transitionportion; and one or more vertical ribs.

The one or more vertical ribs may be coupled to the conical supportportion. The conical support portion may include a conical tension skirthaving a large diameter periphery coupled to the cylindrical supportportion. In some cases, the one or more vertical ribs are coupled to anupper surface of the conical tension skirt.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a nuclear reactor supportstructure, in accordance with some embodiments;

FIG. 2 illustrates a below core support structure for a core-vesselinterface; in accordance with some embodiments;

FIG. 3 illustrates a below core support structure for a core-vesselinterface, in accordance with some embodiments;

FIG. 4 illustrates a below core support structure with a hanging tensionskirt for a core-vessel interface; in accordance with some embodiments;

FIG. 5 illustrates a below core support structure with ribs, inaccordance with some embodiments;

FIG. 6 illustrates a below core support structure independent of thereactor vessel, in accordance with some embodiments;

FIG. 7 illustrates a below core support structure in a bottom-supportedvessel configuration, in accordance with some embodiments;

FIG. 8 illustrates a core support structure configured to hang from thereactor head, in accordance with some embodiments;

FIG. 9 illustrates a core support structure utilizing a cartridge tocouple the core support to the control rod support, in accordance withsome embodiments;

FIG. 10 illustrates a below core support structure and load path throughthe reactor vessel, in accordance with some embodiments;

FIG. 11 illustrates a cartridge core support structure that supports thecore independently of the reactor vessel, in accordance with someembodiments; and

FIG. 12 illustrates a cartridge module, in accordance with someembodiments.

DETAILED DESCRIPTION

This disclosure generally relates to apparatuses for a below-coresupport, such as support for a nuclear reactor vessel, or a nuclearreactor core, which in some cases, is a conical support that transitionsto the cylindrical support of the reactor vessel. In some cases,vertical ribs within the conical support section provide additionalstiffness, rigidity, and support.

In some cases, a core is supported from below, such as by ribs, a skirt,or a platform. In some embodiments, a core is supported by a rim, andmay have structure that engages an upper rim of the core and the corehangs by its rim from the support. In some cases, a vertical cylinderincludes a core support structure and core baffles. The core may beinserted from the top of the reactor and supported by the reactor head.In some embodiments, the disclosed arrangements and support structuresfacilitate shipping of prefabricated and assembled, or partiallyassembled, components and final assembly of the components at a nuclearreactor installation site.

According to some embodiments, a structural cylinder supports a load andtransmits the load to the reactor head. According to some embodiments, acontrol package and core control package may be fabricated and thenlowered into place within the structural cylinder. The structuralcylinder may support the load of the control package and core controlpackage.

The support cylinder may be manufactured in a manufacturing facility andmay include the core barrel and core components already installed beforethe support cylinder is shipped to a reactor installation site. Thesupport cylinder may additionally have a rotating plug, ports, and othercomponents pre-installed prior to shipping to facilitate later assembly,thus improving accuracy, tolerances, and manufacturing and assemblytime.

While the following description is useful in the design and constructionof a sodium-cooled fast reactor (SFR), many of the concepts disclosedherein may be equally applicable to other reactor types, and thedisclosure should not be limited to SFR technology unless specificallystated.

FIG. 1 illustrates a core support structure (CS S) for a nuclear reactorcore. A nuclear reactor includes a core 102 situated within a reactorvessel 104. The reactor vessel 104 is typically closed at its lower endby a bottom head 106 coupled to a cylindrical portion 108. A vessel head110 is mated to the top of the cylindrical portion 108 and closes thereactor vessel 104 and further provides support for reactor internals,such as a rotating plug, core support structures, flow directingmembers, a control element handling system, a fuel element handlingsystem, and other internal vessel equipment.

In many reactors, the reactor vessel 104 is suspended from the reactorhead 110. The reactor head 110, in turn, is supported by structure thatforms part of the building in which the reactor is housed. For example,support structures 112, which may be concrete, are coupled to thefoundation 114. The support structures 112 are additionally supportiveof the reactor head 110 so that the weight of the reactor head issupported in compression by the support structures 112. The reactorvessel 104 typically hangs from the reactor head 110, so its weight isalso borne by the support structures 112, which transmit the load to thefoundation 114.

The reactor vessel 104 contains reactor internals which in some casesinclude the lower core support structure (not shown), the upper coresupport structure, and the in-core instrumentation support structure.The internals are configured to support, align, and guide the corecomponents; direct coolant flow to and from the core components; andguide and support the in-core instrumentation. The lower core supportstructure is typically coupled to the reactor core 102 and transmits theweight of the core 102 to the bottom head 106 of the reactor vessel 104.The lower core support structure may be columns, piers, or othersupports below the core that allow the core 102 to be supported by thebottom head 106 of the reactor vessel 104.

A core barrel supports and contains the fuel components and directs thecoolant flow. In some cases, the core barrel hangs on an upper ledge ofthe reactor vessel. In some cases, the core barrel is allowed tothermally expand in a radial direction and axial direction, buttransverse movement of the core barrel is restricted to inhibitmisalignment with the fuel elements and control elements. The corebarrel may be coupled to the reactor vessel through any suitablestructure that allows the weight of the core barrel to be borne by thereactor vessel from which the core barrel hangs.

With reference to FIG. 2 , a below core support 200 includes a conicalsupport 202 that transitions to the cylinder 204 that interfaces withthe bottom reactor vessel head. One or more vertical ribs 206 aid inlocating and supporting the ex-core barrel shielding and the flow guide.Further, the vertical ribs 206 help to combine the core supportstructure and the core-vessel interface structure into a singlestructure, that may be shippable as a unit. This facilitates fabricatingthe below core support structure in a factory and shipping the coresupport structure to a construction site for assembly.

FIG. 3 shows another example of a below core support structure 300 thatis integral with the reactor vessel bottom head 302. The core supportstructure 300 includes a plurality of ribs 304 to increase stiffness andlateral stability of the core support structure 300. A grid plate 306 issupported by the ribs 304 and provides support for the core which reststhereon. The reactor vessel bottom head 302 is suspended from thecylindrical portion of the reactor vessel.

The integration of the below core support structure 300 into the reactorvessel bottom head provides several advantages. For instance, it reducesthe number of components and assemblies, it is compatible with a reactorvessel auxiliary cooling system (RVACS) and provides a level of lateralstability to support the core.

FIG. 4 illustrates another example of a below core support structure 400in which a conical tension skirt 402 supports a grid plate structure404. The core is supported on the grid plate structure 404 and the loadof the core is transmitted through the conical tension skirt 402directly to the cylindrical portion 406 of the reactor vessel. In somecases, this arrangement avoids the load of the core from being appliedto the reactor vessel bottom head 408, but rather, transmits the coreload directly to the cylindrical portion 406 of the reactor vessel.

The result is a relatively simple fabrication and the conical tensionskirt 402 ameliorates the necessity of internal support from the bottomreactor vessel head 408, routing the core and internals loads throughthe reactor vessel cylindrical portion 406 in tension.

FIG. 5 illustrates an alternate structure for a below core supportstructure 500 that is similar to the structure shown in FIG. 4 with theaddition of ribs 502 above the conical tension skirt 402. The ribs 502support the flow guide and provide coolant channels as well as provideadditional stiffness.

FIG. 6 illustrates an alternative structure for a below core support600. The below core support 600 includes a cylindrical portion 602, anda conical tension skirt 604 depending from the cylindrical portion 602.

The below core support 600, in some instances, is independent from thereactor vessel 606 which may reduce stresses on the reactor vessel 606.In some cases, the below core support 600 may be attached to the reactorvessel 606 by welding to provide intimate surface contact to distributestresses, improve stiffness, and distribute the core load to thecylindrical portion of the reactor vessel 606. In some embodiments, thereactor core can be coupled to the below core support 600, such as in amanufacturing facility (e.g., factory), and the entire core with belowcore support 600 can be lowered into the reactor vessel and assembled tothe reactor vessel at the construction site. Like with many of thedisclosed examples, the components can be fabricated in a manufacturingfacility, partially assembled, shipped to the construction site andfinal assembly can be performed at the construction site efficiently,economically, and with a higher degree of precision than traditionalon-site fabrication techniques provide.

FIG. 7 illustrates an alternative below core support 700 in which theload path of the reactor core is transmitted to a bottom support. Thereactor vessel 702 has a cylindrical portion 704 coupled to a bottomvessel head 706. In some cases, the bottom vessel head 706 rests on oneor more supports to transmit the weight of the reactor vessel 702downwardly eventually to the foundation of the reactor building. In somecases, the below core support 700 is coupled to the reactor vessel 702and the core load is likewise transmitted downwardly to supports andultimately to the foundation of the reactor building. In the examples inwhich the core load is transmitted downwardly to supports below thereactor vessel 702, the core load may not be supported by the reactorvessel 702, and thus the flexibility of the of the reactor vessel 702has a reduced effect on the alignment of the control elements with thereactor core.

Further, the lateral support for the core includes a significant belowcore structure that is tied to the same support from which the reactorvessel 702 is supported. Not only does this significantly reduce theload path for the core load, but also supports the core substantiallyalong its center of gravity and provides a robust core support.

With reference to FIGS. 8 and 9 , a cartridge 800 configuration isillustrated in which the core load is supported vertically through thecore barrel. The cartridge 800 is a generally cylindrical chamber 802that allows the nuclear core to be inserted from the top. The cartridge800 includes a cooperating bottom support structure 804 that interfaceswith the below core support 806 carried by the reactor vessel bottomhead 808. The cooperating below core support structure 804 facilitateslowering the cartridge 800 into the reactor vessel 810 and locating thecartridge 800 with respect to the vessel bottom head 808.

In some cases, the core load is supported by the cartridge 800 to adiscrete portion of the reactor head, which in some cases, also supportsand contains the rotating plug assembly. Utilizing a cartridge 800 asshown and described simplifies factory fabrication and on-site assembly,as the cartridge 800 can be fabricated in a manufacturing facility andassembled with the core and internals pre-installed prior to shipment.

In some cases, the cartridge 800 is supported from above by the reactorhead, which provides the further advantage of coupling the reactor coreto the same load path as the control element support, and thus anydifferential movement of the reactor core and control elements, such asby seismic events, is further reduced.

In the illustrated example, the core support is directly coupled to thecontrol element support, which further reduces the importance of thereactor vessel in providing support to the reactor core, therebyreducing the required precision in fabrication and assembly of thereactor core to the reactor vessel 810.

The reactor vessel 810 may include additional structures required foroperation, such as one or more heat exchangers 812 and one or more pumps814 for circulating coolant through the reactor vessel and the reactorcore.

According to some embodiments, the load chain including the core, thecartridge, and reactor vessel head may be fabricated in a manufacturingfacility and shipped to the construction site as a module for finalassembly. This not only decreases the required on-site fabrication work,but increases efficiency as the reactor vessel, vessel head, andinternals can be lifted and placed in the reactor building. In somecases, the core and cartridge may be manufactured as a module andshipped to a construction site for final assembly with the reactorvessel head being a separate module.

In addition, the illustrated cartridge configuration 800 furtherdecouples the nuclear heat and control module from the heat transportfunctions so that a standard central cartridge 800 and reactor coremodule may be inserted into different nuclear reactor arrangements withminimal changes. In other words, an entire cartridge 800 that includesthe reactor core, control elements, and core internals can be removedfrom a nuclear reactor and a different cartridge 800 can be installed inits place.

FIG. 10 illustrates a schematic diagram of a nuclear reactor 1000including a reactor vessel 1002, a core barrel 1004, and a reactor core1006. The reactor vessel 1002 further includes a vessel bottom head 1008and a vessel head 1010. The vessel head 1010 includes a control elementsupport structure 1012 that supports the control elements 1014, whichmay be used to control reactivity within the nuclear core 1006.

In the illustrated embodiment, the weight of the reactor core is carriedby the core barrel 1004, which in turn is supported by a below coresupport 1016 that transmits the core load to the reactor vessel bottomhead 1008. In some cases, the reactor vessel 1002 is supported by amount, such as a flange, formed in the vessel head 1010 and the reactorvessel 1002 hangs from the vessel head 1010. Thus, the weight of thereactor vessel, along with the reactor core and core barrel, issupported by the vessel head 1010. In some instances, there may befurther support structures, such as beneath the reactor vessel 1002, oradjacent to the reactor barrel 1004 to support against lateral loads.

One area of sensitivity in the construction of a nuclear reactor is theresponse of the reactor internals to a seismic event. For example, aseismic event may cause the reactor vessel 1002 to move both laterallyand axially in response to seismic forces. Similarly, the controlelements 1014 may also move in response to seismic forces. Where thereis differential movement between the control elements 1014 and thereactor vessel 1002, reactivity within the reactor core 1006 isaffected. In addition, fabricating the control element support 1012, andthe structures that align the core 1006 with the control elements 1014is a fabrication that requires tight tolerances and high-qualityfabrication in order to ensure safe and predictable reactor operation.

In the illustrated embodiment, the weight of the core is borne by thereactor vessel 1002. The weight of the control elements 1014, on theother hand, is carried by the control element support 1012 that forms apart of the vessel head 1010. In a seismic event that causes movement ofthe reactor vessel 1002, the motion about the reactor vessel head 1010will translate to lateral movement of the control elements 1014 about apivot point located substantially at the vessel head 1010. In contrast,the reactor core 1006 will experience movement associated with theheight of the reactor vessel 1002. In other words, the reactor core 1002will experience movement that is related to the vessel bottom head 1008that has a magnitude of movement proportional to the height of thereactor vessel 1002. In many cases, a seismic event will tend to cause agreater degree of lateral movement of the core 1006, which is supportedby the reactor vessel 1002, in comparison to the movement of the controlelements 1014. The differential movement of the core and controlelements 1014 can cause swings in reactivity that may be undesirable andunpredictable.

FIG. 11 illustrates a schematic diagram of a nuclear reactor 1100including a reactor vessel 1002, a core cartridge 1102, and a reactorcore 1006. The reactor vessel 1002 further includes a vessel bottom head1008, and a vessel head 1010. The vessel head 1010 includes a controlelement support structure 1012 that carries one or more control elements1014. The control element support structure 1012 is coupled to the corecartridge 1102 so that the core cartridge 1102 hangs from the controlelement support structure 1012. Thus, the load path for both the reactorcore 1006 and control elements 1014 are coupled together by sharing acommon support structure 1012 that supports both the control elements1014 and the reactor core 1006. The result is a significant reduction indifferential movement between the control elements 1014 and the reactorcore 1006, such as in response to a seismic event.

Moreover, the illustrated configuration provides a cartridge 1102 thatcan be fabricated in a factory, shipped to the construction site, andlowered into the reactor vessel, even after the reactor vessel 1002 hasbeen installed within the reactor building. In some cases, the cartridge1102 can be manufactured in a factory to include the reactor core 1006and the core internals prior to shipping. This improves accuracy in thefabrication of delicate components, reduces the amount of on-sitefabrication work, and greatly reduces the time required to install thecomponents on site.

In addition, the illustrated embodiment reduces complexity and removesreliance on the reactor vessel 1002 wall to support the reactor core1006. As described herein, a first cartridge 1102 may be removed fromthe reactor vessel 1002 and replaced with a second cartridge 1102, whichin some embodiments, has a different configuration from the firstcartridge.

FIG. 12 illustrates a cartridge core barrel 1200 including a generallycylindrical cartridge 1202, a reactor core 1006, and a control elementsupport 1204. The control element support 1204 may include a pluralityof apertures for allowing control elements 1014 to be selectivelyinserted and withdrawn from the core 1006. The cartridge core barrel1200 includes mounting structures 1206 which may include one or moreflanges configured to engage with cooperating structures on a reactorvessel head, thus hanging the cartridge core barrel 1200 from thereactor head. The cartridge core barrel 1200 may further include belowcore support 1208 that may be configured to cooperating with matingstructure on the reactor vessel bottom head to provide further supportto the cartridge core barrel 1200.

In some embodiments, the cartridge core barrel 1200 can be fabricated ina manufacturing facility and shipped to the construction site as amodule. The reactor core barrel 1200 may be fabricated to include thereactor core 1006, any core internals, control element drive system, andthe control element support 1204. The load path of the control elements1014 and the reactor core 1006 is coupled together so that motionassociated with the reactor vessel head transmits motion to both thereactor core 1006 and the control elements 1014 with the same directionand magnitude. This allows the control elements 1014 to remain alignedwith the reactor core 1006 to a level never before achieved in reactorsin which the load path of the reactor core and the control elements arenot coupled together through a common load path.

In addition, the cartridge core barrel 1200 can be manufactured as amodule and installed within the reactor vessel after the reactor vesselhas been installed within the reactor building, which improves theefficiency in assembly, reduces on-site fabrication, and increasestolerances by virtue of fabricating and assembling the modules within amanufacturing facility. According to some embodiments, the cartridgecore barrel 1200 can be fabricated as a module to include the reactorcore, rotating plugs, and the control elements support structure. Thismodule can be manufactured within a factory to have tight tolerancesthat are very difficult to achieve with on-site fabrication techniquesand the module with its internal components already installed, can thenbe shipped to the construction site for installation.

In some embodiments, the cartridge core barrel 1200 is a single moduleand the reactor vessel may be a separate module. In some cases, thereactor vessel can be sliced into segments along its longitudinal axisto aid in transport and assembly. For example, the reactor vessel can besegmented into cylindrical segments having a suitable length, such as 8feet, 10 feet, 12 feet, or 15 feet or more to aid in transporting thereactor vessel to the construction site. The segments can be joinedtogether on site and may be joined together in place within the reactorbuilding, such as by placing and installing a first segment in placewithin the reactor building, then attaching a second segment to thefirst segment, and so on. Once the reactor vessel is assembled andinstalled within the reactor building, the cartridge core barrel 1200can be lowered into the reactor vessel and located within the reactorvessel by aid of the below core supports 1208. The support structure forlocating the control elements relative to the reactor core requires ahigh-precision fabrication process, which is much easier to be met byproviding a cartridge core barrel 1200 that is fabricated in amanufacturing plant and shipped to the construction site, and in somecases, includes the reactor core and other internal componentspre-assembled prior to shipping. This greatly simplifies construction,increases precision, and does not rely on the reactor vessel to supportthe weight of the reactor core. By removing the reactor vessel from thereactor core load path, the reactor vessel can be fabricated to be lessrobust with looser tolerances, which translates to a reduction in timeand cost to fabricate the reactor vessel. In other words, the reactorvessel is decoupled from the cartridge core barrel 1200 and the reactorcore 1006, and in some cases, there is no reactor vessel participationin support of the reactor core. However, in some embodiments, thereactor vessel may include one or more spacers in the annulus betweenthe reactor vessel and the cartridge reactor core barrel to providelateral stability in a radial direction.

The cartridge core barrel 1200 may incorporate any suitable below coresupports 1208, such as any of the structures shown and described inrelation to FIGS. 2-7 . Moreover, the concepts presented herein may beapplicable to any reactor type, and are especially suitable for reactorsthat rely on near-atmospheric pressure conditions.

The disclosure sets forth example embodiments and, as such, is notintended to limit the scope of embodiments of the disclosure and theappended claims in any way. Embodiments have been described above withthe aid of functional building blocks illustrating the implementation ofspecified components, functions, and relationships thereof. Theboundaries of these functional building blocks have been arbitrarilydefined herein for the convenience of the description. Alternateboundaries can be defined to the extent that the specified functions andrelationships thereof are appropriately performed.

The foregoing description of specific embodiments will so fully revealthe general nature of embodiments of the disclosure that others can, byapplying knowledge of those of ordinary skill in the art, readily modifyand/or adapt for various applications such specific embodiments, withoutundue experimentation, without departing from the general concept ofembodiments of the disclosure. Therefore, such adaptation andmodifications are intended to be within the meaning and range ofequivalents of the disclosed embodiments, based on the teaching andguidance presented herein. The phraseology or terminology herein is forthe purpose of description and not of limitation, such that theterminology or phraseology of the specification is to be interpreted bypersons of ordinary skill in the relevant art in light of the teachingsand guidance presented herein.

The breadth and scope of embodiments of the disclosure should not belimited by any of the above-described example embodiments, but should bedefined only in accordance with the following claims and theirequivalents.

Conditional language, such as, among others, “can,” “could,” “might,” or“may,” unless specifically stated otherwise, or otherwise understoodwithin the context as used, is generally intended to convey that certainimplementations could include, while other implementations do notinclude, certain features, elements, and/or operations. Thus, suchconditional language generally is not intended to imply that features,elements, and/or operations are in any way required for one or moreimplementations or that one or more implementations necessarily includelogic for deciding, with or without user input or prompting, whetherthese features, elements, and/or operations are included or are to beperformed in any particular implementation.

The specification and drawings disclose examples of systems, apparatus,devices, and techniques that may allow modules of a nuclear reactor tobe fabricated in a manufacturing facility and shipped to a constructionsite, where the modules can be assembled, thereby greatly reducingon-site fabrication complexity and cost. Further, the systems of thenuclear reactor have been simplified and further promote factoryfabrication in lieu of on-site fabrication.

A person of ordinary skill in the art will recognize that any process ormethod disclosed herein can be modified in many ways. The processparameters and sequence of the steps described and/or illustrated hereinare given by way of example only and can be varied as desired. Forexample, while the steps illustrated and/or described herein may beshown or discussed in a particular order, these steps do not necessarilyneed to be performed in the order illustrated or discussed.

The various exemplary methods described and/or illustrated herein mayalso omit one or more of the steps described or illustrated herein orcomprise additional steps in addition to those disclosed. Further, astep of any method as disclosed herein can be combined with any one ormore steps of any other method as disclosed herein.

It is, of course, not possible to describe every conceivable combinationof elements and/or methods for purposes of describing the variousfeatures of the disclosure, but those of ordinary skill in the artrecognize that many further combinations and permutations of thedisclosed features are possible. Accordingly, various modifications maybe made to the disclosure without departing from the scope or spiritthereof. Further, other embodiments of the disclosure may be apparentfrom consideration of the specification and annexed drawings, andpractice of disclosed embodiments as presented herein. Examples putforward in the specification and annexed drawings should be considered,in all respects, as illustrative and not restrictive. Although specificterms are employed herein, they are used in a generic and descriptivesense only, and not used for purposes of limitation.

Unless otherwise noted, the terms “connected to” and “coupled to” (andtheir derivatives), as used in the specification, are to be construed aspermitting both direct and indirect (i.e., via other elements orcomponents) connection. In addition, the terms “a” or “an,” as used inthe specification, are to be construed as meaning “at least one of”Finally, for ease of use, the terms “including” and “having” (and theirderivatives), as used in the specification, are interchangeable with andhave the same meaning as the word “comprising.”

From the foregoing, and the accompanying drawings, it will beappreciated that, although specific implementations have been describedherein for purposes of illustration, various modifications may be madewithout deviating from the spirit and scope of the appended claims andthe elements recited therein. In addition, while certain aspects arepresented below in certain claim forms, the inventors contemplate thevarious aspects in any available claim form. For example, while onlysome aspects may currently be recited as being embodied in a particularconfiguration, other aspects may likewise be so embodied. Variousmodifications and changes may be made as would be obvious to a personskilled in the art having the benefit of this disclosure. It is intendedto embrace all such modifications and changes and, accordingly, theabove description is to be regarded in an illustrative rather than arestrictive sense.

What is claimed is:
 1. A method of constructing a nuclear reactorcomprising: fabricating, in a manufacturing facility, a reactor vessel;fabricating, in the manufacturing facility, a core barrel; fabricating,in the manufacturing facility, a reactor core; fabricating, in themanufacturing facility, a control element drive system; assembling, inthe manufacturing facility, the control element drive system and thereactor core within the core barrel to create a core module; shippingthe core module to a construction site; fabricating, in a manufacturingfacility, a vessel head configured to be mounted to an upper end of thereactor vessel; assembling the vessel head with a control elementsupport structure, wherein the control element support structure ismounted to the reactor vessel head, wherein the control element supportstructure is configured to carry one or more control elements; andassembling the core barrel to the control element support structure,wherein the core barrel hangs from the control element supportstructure, wherein the control element support structure is configuredto support weight of each of the one or more control elements, the corebarrel, and the reactor core.
 2. The method of constructing a nuclearreactor as in claim 1, further comprising shipping the reactor vessel tothe construction site.
 3. The method of constructing a nuclear reactoras in claim 2, further comprising installing the reactor vessel in areactor building.
 4. The method of constructing a nuclear reactor as inclaim 3, further comprising placing the core module inside the reactorvessel.
 5. The method of constructing a nuclear reactor as in claim 4,further comprising coupling the core module to a first portion of thereactor vessel head.
 6. The method of constructing a nuclear reactor asin claim 5, further comprising coupling the control element drive systemto the first portion of the reactor vessel head.
 7. The method ofconstructing a nuclear reactor as in claim 1, wherein fabricating thecore barrel comprises forming the core barrel as a cylinder.
 8. Themethod of constructing a nuclear reactor as in claim 7, wherein the corebarrel is configured to receive the reactor core and support the weightof the reactor core.
 9. The method of constructing a nuclear reactor asin claim 1, further comprising constructing a below core supportstructure configured to link the core barrel to a lower portion of thereactor vessel and limit relative motion between the core barrel and thereactor vessel.
 10. The method of constructing a nuclear reactor as inclaim 1, wherein the control element drive system is configured to beinserted into the core barrel and supported by the core barrel.